Key Points

  • The Ninth Circuit reversed the denial of a preliminary injunction and directed the district court to enjoin California, Gov. Gavin Newsom and Attorney General Rob Bonta from enforcing Section 10 of the No Vigilantes Act against the United States, federal agencies and federal officers.
  • The panel held that Section 10, which requires non-uniformed federal officers to visibly display their agency and a name or badge number during enforcement duties, directly regulates federal governmental functions without congressional authorization and is barred by intergovernmental immunity.
  • The court rejected the district court's and California's substantial-burden standard, holding that it applies to regulation of federal contractors, and that intergovernmental immunity from direct regulation has no de minimis exception.
  • The panel held that the United States satisfied the facial-challenge standard and is "certain to succeed" on the merits, and that the remaining preliminary-injunction factors favor the government.
  • The opinion adopts, for precedential purposes, the panel's April 2026 analysis granting an injunction pending appeal.

California cannot require non-uniformed federal law enforcement officers to wear visible identification while they make arrests or control crowds in the state, a federal appeals court held on Oct. 14, ordering a trial judge to block the state from enforcing the rule against federal agents.

A three-judge panel of the U.S. Court of Appeals for the Ninth Circuit reversed U.S. District Judge Christina A. Snyder of the Central District of California, who had denied the federal government a preliminary injunction. Judge Mark J. Bennett wrote for the panel, which also included Judges Jacqueline H. Nguyen and Daniel P. Collins. "Indeed, we conclude that the United States is certain to succeed," Judge Bennett wrote.

The decision converts the panel's emergency-stage ruling into an instruction to the trial court. The same panel had barred enforcement of the identification requirement on April 22 while the appeal was pending, after hearing argument, and the new opinion adopts that earlier analysis "including for precedential purposes." The panel also held that a state law directly regulating federal law enforcement is void however lightly it burdens federal operations.

The provision at issue is Section 10 of the No Vigilantes Act, which California enacted on Sept. 20, 2025, in response to what the statute calls the United States's "broad immigration enforcement efforts." It requires any non-uniformed officer, expressly including "any federal law enforcement officer," to "visibly display identification that includes their agency and either a name or badge number or both name and badge number when performing their enforcement duties."

The law defines enforcement duties as operations "involving the arrest or detention of an individual, or deployment for crowd control purposes." A willful and knowing violation is a misdemeanor. The statute exempts undercover work, SWAT teams, exigent circumstances and several other situations. It also spares any agency that publicly posts a written identification policy under a companion provision, Section 2.

On the same day, California enacted the No Secret Police Act, which bars officers, including federal agents, from wearing face coverings that conceal their identity. The United States sued the state, Gov. Gavin Newsom and Attorney General Rob Bonta on Nov. 17, 2025, challenging parts of both laws under the Supremacy Clause.

Judge Snyder ruled for each side in part. The district court preliminarily enjoined the mask ban against federal officers, finding that it likely "unlawfully discriminates against the federal government." But Judge Snyder refused to block the identification requirement, reasoning that "the United States ha[d] not shown that its current practices with respect to . . . identification are essential to federal law enforcement operations." The government appealed only the identification ruling.

The appeal turned on intergovernmental immunity, a Supremacy Clause doctrine under which, as the opinion put it, "states may not directly regulate the Federal Government's operations or property." The panel held that Section 10 falls within that bar. "Section 10 explicitly overrides the federal government's power to determine whether, how, and when to publicly identify its officers," Judge Bennett wrote. Because Congress had not authorized such regulation, the panel held, the law is invalid.

The United States had brought a facial challenge, one attacking the law in all its applications before California enforced it against anyone. That posture required the government to show that "no set of circumstances exists under which the Act would be valid." The panel held that the government met the standard because Section 10 "exclusively regulates quintessentially government conduct: law enforcement."

California argued that a state law counts as impermissible direct regulation only if it "impose[s] substantial burdens on federal operations," and the district court had agreed. "This was error," Judge Bennett wrote. The panel held that the substantial-burden test governs state regulation of federal contractors and third-party employers, not of the federal government itself, and that the immunity has no de minimis exception, meaning that it applies however small the intrusion.

A state law that directly regulates federal conduct without congressional authorization "is void irrespective of whether the regulated activities are essential to federal functions or operations, and irrespective of the degree to which the state law interferes with such functions or operations," the court wrote.

The panel also distinguished a 1920 Supreme Court decision, Johnson v. Maryland, which suggested that states might apply to federal officers general rules such as "a statute or ordinance regulating the mode of turning at the corners of streets." Traffic laws reach conduct any citizen could engage in, the panel wrote, but "ยง 10 applies exclusively to law enforcement officials and exclusively to their performance of law enforcement operations." The court left open whether Johnson creates an exception for generally applicable laws.

The court likewise rejected California's argument that the facial challenge should fail because individual officers prosecuted under the law could raise a case-by-case immunity defense by showing an honest and reasonable belief that their conduct was necessary. "The immunity at issue here, however, belongs to the United States, which enjoys a distinct form of immunity under the Supremacy Clause: intergovernmental immunity," Judge Bennett wrote.

The remaining injunction factors followed from the merits ruling. Irreparable harm, the panel wrote, "necessarily results" from letting California enforce "a law we hold is invalid, ab initio, under the Supremacy Clause." The panel added that the balance of equities and the public interest tipped "decisively" toward the United States.

Andrew M. Bernie of the Justice Department's Civil Division appellate staff argued for the United States. Deputy Solicitor General Mica L. Moore of the California Attorney General's office argued for the state. Burt M. Rublin of Ballard Spahr LLP represented amicus curiae Citizens for Responsibility and Ethics in Washington.

The case now returns to the district court with instructions to enter a preliminary injunction barring California, its governor and its attorney general from applying or enforcing Section 10 against the United States, federal agencies and federal officers. The district court's injunction against the mask ban, which no party appealed, remains undisturbed, as do its rulings that the government lacks standing to challenge the two laws' written-policy provisions.